i watched some movies this weekend on my db. it goes low enough. not subsonic, but enough for me. (usable down to about 35hz)2 of those would be fantastic. if you choose pr, you would need 1 12pr for each 10. as far as jj was saying.i want to buy something similar and put it in a db10. my plan is to mount with the magnet in the vented part and put a small plexi window (at least 10mm thick) on the top lid, so i can se the pretty xcursion (xmax = 20 mm :-* ). that's the only bad part about the db10. you can't see the mofo moving :(

SO its now between the 2 Table Tubas or a single WO. Degree of difficulty for 2 tubas is prolly what I would say is for a single WO. SO it comes to how I want to allocate my space. I think I could easily fit two tubas or a single WO.

I've also got a weird iso-box I designed, but it's completely untested and unbuilt. It's supposed to appear as a coffee table, but act as a very defining HT sub utilizing two 10" woofers.[/hijack](sorry)

I'm kinda on the fence. I think I'd trust the WO more, but I'd like the experience of building and trying something else.

I have no experience with the table tuba but the frequency response chart doesn't look so good. And that is measured corner response. Put it out in the middle of the room and it would probably be much worse.

Jet, you are the one that got me started with the whole tl thing. So what's wrong with the transflex? I'm planning on putting a modified box together within the next few weeks.

For HT I would personally select the PR's as they act like ports, without port noise, plus they allow for a great deal of tuneability. 1 12" PR is sufficient for 1 10" driver, but you could use a 15" radiator to good effect, just remember not to weigh it down to start.

The not so basics of PRs are that they;

i. produce sound, often at subsonic frequenciesii. Control the movement of the driver's cone and voicecoiliii. control the total Q of a system through weightiv. smooth out peaks in resistance on the driver, making them easy to power.

Its a short list, that looks simple, but when you get into it you start to realize just how easy it would be to tune the system totally wrong and get crappy sound.

Start with the PR's totally unweighted in a box around 2.5 cubes, maybe 3 if using the 15" PR. Likely if you do, the Fs of them will be around 13hz to begin with. Use your computer to run some sine sweeps in the 10-30hz range, and look to see what both the driver and the PR are doing.

If the driver is getting close to, or hitting its limits around 20hz, but the output is insufficient, then add weight to the PR in 50g increments until your driver behaves itself at the required level. On a cautionary note, theres only so much weight you can add before the efficincy of the whole system goes down, so if it seems like you add more, but nothing changes you have likely passed the maximum potential of the system. When you build the boxes, build them so that its easy to get the PR in and out, use inserts or t-nuts to keep the holes from stripping out as you will definitely be doing some tuning.

The PR will also change the power handling and resistance characteristics of your driver, too much weight and the coil will run too hot, but likely with as much sd as you have with the 15" PR, your coil will be fine. The sd is the radiating surface area and in the end determines the extra force applied to the driver as it approaches its limits, like a brake.

Anyways, your system will definitely be overdamped, or close to it because of the sd of the 15" PR. Theres nothing wrong with that, I personally prefer the overdamped characteristics. My ideal system, still on the drawing board, uses a 10" driver, with big Xmax, coupled to two 10" PRs with huge Xmax in about 2 cubes. On paper the system should, with two boxes ( 2x driver, 4x PR total in two two cube cabs) for dipole setup "should" be +/-3db from 21hz to the low pass XO frequency around 112db on about 250W/cabinet. This system is also overdamped, and could be louder, however, the point of balance for the system lies right around 250W, so the system can be turned up to maximum without fear of damaging any of the components. I have yet to build this, however, i do have a few other experiences with this alignment, both good and bad and can tell you for certain, that for HT, a PR cab is the only way to go. Seriously, nothing wrecks war of the worlds like horrible port noises in the middle of the cool explosions, same for popping coils off of backstops when T-rex goes for the truck in Jurrassic Park 1.

For HT, IMHO, you need the big output down low to be consistent as, unlike music, most movies contain track information below 20hz (well DVDs anyways). You might not be able to hear that, but you can feel it, but unless your system can really take it theres likely not too much good in trying to reproduce it. A PR system has a sharp sharp dropoff in output below the PRs Fs, almost like a rumble filter at 24db/octave allowing you to take a 10" driver right to its limits in a controlled manner without making it reproduce frequencies it really cant.

It sounds like a lot more work, but when its perfect, boy, is it perfect. IMHO its the way to go, like you couldnt tell LOL

If the sub and the amp are already a match for one another, then a PR alignment will allow you to make a lot of headroom, that is a good thing, likely you could push those 350W drivers with as much as 500W in a properly tuned setup, however, whatever volume you have at 350W will only increse by 3db if you DOUBLE the power, so an extra 150W wouldnt make much difference at all. Power handling department is fine for a PR alignment.

honestly, a graph of a PR box in winISD looks like it does have a rumble filter. If you had insufficient sd, ie, only 1 10" PR then I would say yes to the filter, but no to the build. With a 15" PR i doubt you will have a need. Getting such a large cone moving, and keeping it moving, will provide sufficieint damping in the low range to keep the driver behaving well.

If it does seem like theres too much movement going on, then add more weight to the PR. FWIW minimum weight that makes a difference is only about 200g away from optimal, which is only about 200g away from well overdamped.